Indonesian students work during a regional hacking competition in Denpasar, Bali, Indonesia, in 2007.

Indonesia isn't known as an epicenter for hacking, but the Southeast Asian country was the source of 21 percent of the world's cyber-attack traffic in the first quarter of this year, according to a report by Akamai Technologies to be published later today.

The type of activity observed in Indonesia suggests an aggressive botnet attack, according to the study. A botnet takes control of hordes of personal computers by infecting them with malicious software that forces them to do a hacker's bidding.

The latest data represent a sudden shift for Indonesia, which accounted for less than 1 percent of online assaults in the fourth quarter of last year, according to Akamai. This year, the country has generated several headlines related to cyber-attacks.

In January, hackers protested the treatment of one of their own in Indonesia by defacing government websites. Then in May, China's official Xinhua News Agency reported that Indonesia plans to set up a "cyber-army" after the recent barrage of hacking attacks. And in June, Microsoft said it had disrupted a widespread cybercrime operation that originated in Indonesia, among other countries, according to Reuters.

Indonesia ranked No. 2 in global attack traffic behind China, which accounted for 34 percent. In third place with 8.3 percent was the U.S., which has steadily become a smaller source of digital assaults over the last few quarters amid the rise of Asia and Eastern Europe. Turkey and Russia rounded out the top five on Akamai's list.

Indonesia, Hong Kong and India were the only places in the top 10 where the volume of attacks increased compared with the previous quarter, according to the report. The study is based on traffic flowing through Akamai's network, which companies use to help speed the delivery of online content.